A couple weeks ago we showed you our best tips for the Google Finance Stock Screener. But this tool is just one of many features on the site that is designed to help you make informed investing decisions. Today we’d like to reintroduce you to Google’s Domestic Trends - a powerful tool for exploring the economy and financial markets. We first introduced Google Domestic Trends last September in partnership with Hal Varian and the Google team of economists. The ultimate goal was to explore the link between relative search query volume of terms related each of 23 major economic industries in the United States and stock market performance. In this way, we sought to provide unique insight into the broader economy and help users to take a holistic view of the market. The tool is easy to use - just select the industry you’re interested in to see a sample of the keywords we track for that industry. Then, compare searches for those terms with price performance of the major market indices or individual stocks. As a reminder, each index value is set to 1.0 as of January 1, 2005 and is calculated and displayed on the Google Finance charts as a 7-day moving average. You can easily compare actual stocks and market indexes to these Google Trends on the charts.To mark the anniversary of these tools, the Google Finance team decided to have some fun with the data to see what interesting trends we could find. Here are some of our favorites:Luxury GoodsOver the past year, the luxury goods index has shown a predictable pattern with spikes in searches for terms related to jewelry, diamonds, and more around the winter holiday season and Valentine’s day. However, the comparison chart below shows that the traditional luxury goods stocks did not show huge spikes during those periods and instead followed the trend of the broader market index (in this example, the Dow Jones Index), including a continued trend upwards in spring of this year even as relative searches for luxury goods fell, with the exception of the Valentine’s day spike in February. Automotive IndexOver the lifetime of the Domestic Trends Index, we’ve seen a regular spike in search traffic for automotive related queries each summer - regardless of broader market performance. In 2010, however, the spike was significantly smaller, as shown in the graph below. The stock performance of most major automotive stocks for 2010, reflects this trend. With the marked exception of Ford Motor Company, which is up nearly 19.7% as of September 14, and Tata Motors which is up 40.8% for the year, other major automotive stocks are all down for 2010. Explore Domestic Trends to discover more interesting trends and indicators for the economy and markets. And to catch the latest from the Google Finance team, follow us onTwitter.